1. Field of the Invention
The present invention relates to an ink jet printer head featuring the use of a piezoelectric thin film as a drive source for ink discharge, and to a method for manufacturing the same.
2. Description of the Related Art
Examples of electromechanical transducer elements serving as a drive source for liquid or ink discharge include piezoelectric ink jet printer heads featuring the use of a piezoelectric thin film consisting of PZT. Such a printer head can be manufactured by the following process, for example, using an etching technique.
A silicon thermal oxide film, a common electrode serving as an vibrating plate, a piezoelectric thin film, and a top electrode are formed, in that sequence, on a silicon substrate which is to be used as the ink jet base. The piezoelectric thin film and top electrode are then patterned using a negative resist, and a piezoelectric element is thus formed by means of the common electrode, piezoelectric thin film, and top electrode. Anisotropic etching of the underside of the head base (the side opposite where the piezoelectric thin film is formed) results in the formation of 0.1 mm wide ink pressure generating chambers, ink supply channels that supply ink to the ink pressure generating chambers, and an ink reservoir that is connected to the ink supply channels; and a nozzle plate is connected, in which nozzle holes have been formed to discharge the ink to locations corresponding to the ink pressure generating chambers.
However, the process for forming patterns including such a piezoelectric thin film on an ink jet base is carried out at elevated temperatures, resulting in the need for quartz glass as well as a silicon substrate with excellent heat resistance for the ink jet base.
Such silicon substrates and quartz glass are scarce and extremely expensive materials, however, and they are also brittle and quite susceptible to cracking. This results in poor manufacturing yields and higher costs.
There has also been recent demand for more precise formation of ink jet nozzle holes to achieve higher density in the dot patterns of ink jet printer heads, but it has been difficult for the following reasons to manufacture nozzle plates in conventional methods in order to meet such demand. Conventionally, SUS plates with a thickness t of 100 to 60 xcexcm have been punched to make holes. Fine holes not only make the punching process more difficult, and also result in a lower punch life.
An object of the present invention is thus to provide an ink jet printer head in which the material for the ink jet base is not limited, as well as a method for manufacturing the same. Another object of the present invention is to provide a method for manufacturing an ink jet printer head allowing greater dot pattern density to be achieved, as wall as an ink jet printer head that is manufactured by this manufacturing method.
The applicant has proposed a method in which a separable material on a substrate with a separation layer interposed between them is separated from the substrate, wherein the separation layer is irradiated with light to effect the separation in the interior layer of the separation layer or at the interface, and has also proposed that this method could be applied for piezoelectric element actuators (Japanese Patent Application 8-225643).
The present application is intended for application in methods of manufacturing ink jet printer heads, and is intended to provide a method for manufacturing an ink jet printer head in which a piezoelectric element and an vibrating plate for pressurizing the ink in an ink pressure generating chamber is formed on an ink jet base on which the ink pressure generating chambers are formed, wherein the method for manufacturing an ink jet printer head comprises the steps of forming the piezoelectric element and the vibrating plate on the substrate with a separation layer interposed therebetween; of bonding the substrate and the ink jet base; and of irradiating the separation layer with light so that the substrate is separated from the vibrating plate, on which the piezoelectric element has been established, at the separation layer, and of joining the vibrating plate with the ink jet base, thereby achieving the objectives described above.
The piezoelectric element has a structure in which the piezoelectric thin film is sandwiched between electrodes, although a variety of electrode configurations can be considered.
The present invention is also characterized by an ink jet printer head formed by these processes, as well as by printers so equipped.
This method allows the ink jet base to be formed by a different process than the process for forming the piezoelectric thin film, and thus allows the ink jet base to be formed without being limited to conventional materials or manufacturing methods.
Methods that can be used during the formation of the ink jet base include a method of formation using photosensitive glass, a method of formation using a photosetting resin, a method of formation using electroformation, or a method of formation using a stamper. These methods can be used to integrally form a conventional nozzle plate with the ink jet base, and to form ink jet nozzle holes in higher density dot patterns.
Quartz glass is preferably used as the substrate in the present invention.